Which of the following conditions involves invasion of the placenta into the uterine myometrium?

• A. Placenta accreta
• B. Placenta previa
• C. Placenta percreta
• D. Placenta increta

Answer: (D)

Increta is when placental tissue invades into the muscular layer of the uterus, the myometrium. This depth of invasion distinguishes it from the other placentation abnormalities: accreta, where the placenta attaches to the myometrium surface but does not penetrate deeply; and percreta, where invasion goes through the myometrium and into the serosa or adjacent organs. Placenta previa, by contrast, refers to implantation in the lower uterine segment and is not about how deeply the placenta invades the uterine wall. So, invasion into the myometrium specifically points to increta.